The present invention relates to an external device for the drainage of biological fluid, particularly cephalorrhachidian fluid.
The invention relates more particularly to ventricular drainage devices intended to regulate intracranial pressure. However, the drainage site could also be the lumbar space, the subarachnoid space, or any other site that allows drainage, particularly of cephalorrhachidian fluid.
There are already several known types of implantable valves intended for controlling the drainage of excess cephalorrhachidian fluid contained in the cerebral ventricles, for example the peritoneal cavity. These valves are generally intended for the treatment of hydrocephalus.
Thus, the use of simple pressure regulating valves is known. The drawback of these valves is that they do not take into account the differences in the water level that result from of the position of the patient, particularly when lying down or standing.
It has also been proposed to use needle and diaphragm valves having a so-called xe2x80x9canti-siphonxe2x80x9d feature, thus avoiding the above drawback. Although often satisfactory, they are intended to be implanted, and therefore are not suitable for short-term use, for example following a trauma.
The known external drainage systems are constituted by a simple catheter, one end of which is disposed in the area to be drained, and the other end of which is connected to a drainage bag. Since they have no pressure regulating means having an xe2x80x9canti-siphonxe2x80x9d type feature, they do not allow the patient to stand. Moreover, their settings need to be checked after the patient is moved (washing, transporting, etc.).
The simple addition of a pressure regulator does not constitute a suitable solution. These regulators are in fact relatively complicated devices subject to obstructions if the cephalorrhachidian fluid is mixed with blood. Moreover, their cost is high.
The object of the present invention is to overcome the disadvantages of the prior art devices.
To this end, the subject of the invention is an external device for the drainage of biological fluid, particularly cephalorrhachidian fluid, comprising a catheter, one end of which is disposed in the area to be drained and the other end of which is connected to a drainage bag, characterized in that it comprises pressure measuring means for measuring the pressure in the area to be drained, and external flow control means controlling flow through the catheter, an electronically controlled power supply being provided for actuating the flow control means when the pressure exceeds a predetermined threshold.
Thus, the pressure in the area to be drained is regulated directly and simply. The flow control means and their power supply are outside the cephalorrhachidian fluid circuit and are therefore reusable. Only the catheter, the drainage bag, and possibly the pressure measurement means if the fluid to be drained has direct contact with them, are disposable.
In the case of external ventricular drainage, a device of this type is not sensitive to the position of the patient, who can stand up and move, or be moved, without any adjustment of the system.
Various types of flow control means can be used.
In a first case, this could be progressive means such as a pump or a valve operated by a motor.
In another case, this could be a means that operate in an all-or-nothing mode such as a pinch valve or flap valve.
In the latter case, the valve is normally closed and opens when the pressure threshold is reached. This opening can occur in pulses, the pulses continuing until the pressure has fallen back below the threshold.
In one particular embodiment, the pressure measuring means is disposed on a drainage line. More particularly, the means can be disposed between one catheter part, one end of which is inserted into the ventricle to be drained, and another catheter part connected to the drainage bag.
However, in another embodiment, it is possible to use an independent implantable catheter comprising a sensor in its distal part. In the case of ventricular drainage, it is possible to use any other means for measuring intracranial pressure that issues a signal compatible with the electronic control of the power supply.
In another particular embodiment, the electronic control is disposed to read the pressure at predetermined time intervals, and if the pressure is higher than the threshold, to activate said flow control means for a duration that is also predetermined.